For the examination of the spinal canal, the sodium salt of monoiodomethanesulfonic acid (methiodal sodium) has been utilized for a long period of time. Compared to oily contrast media, this compound has the advantage of being rapidly and entirely resorbable. The very low viscosity of compositions comprising this compound makes it possible for the medium to penetrate into the finest fissures and thus render an excellent representation of the details in myelography. Disadvantages are the limited representation of the lumbar region and the necessity of prior spinal anesthesia, which constitutes a source of side reactions. According to SCHOBER (Radiopaque Agents and Liquor Space, Springer publishers 1964) a large number of the dangerous complications, such as conditions of shock and collapse, are ascribed to lumbar anesthesia.
It has now been found that the novel salts of this invention possess such a high compatibility with respect to the neural tissue that a lumbar anesthesia with its associated risks becomes superfluous. This essential advantage is attained without a reduction of the favorable properties of the known sodium salt, such as low viscosity and rapid resorption. Rather, the excellent compatibility of the novel salts permits readily a doubling of the commercially customary concentration of about 100 mg. of iodine per ml. of salt solution to 200 mg. of iodine per ml. of salt solution, whereby the image quality and thus the possibilities of evaluation of the myelographic examination are considerably increased.